4 inch Duct Connector, 2 Pack Plastic Straight Pipe Flanges, Ventilation Ducting Connector for Heating Cooling Ventilation System

Built a box and made a cutout for this for roof vent exhaust fan with 4 inch exhaust hose. Works perfectly for the job I used it for

They work fantastically. I used one to attach a 4" hose to my laser enclosure which came with a 3" port. Now I get better flow and this truly takes care of the miniscule amount of fumes that were escaping previously.

Works as intended.

Works great using them on a couple vevor diesel heaters. Makes it easy to hook up 4” ducting to both inlet and outlets of the heaters.

Used on the side of a box that houses my laser engraver.

I use these for my printing enclosure to vent out fumes. It’s very sturdy and secure, holds the vent tube well, and doesn’t come loose.

Exactly what I needed to vent bathroom to attic vent

I bought these to use on the end of a diesel heater, so I can connect a dryer hose easier. They work, but they are pretty brittle. While screwing it on, I started to hear what sounded like a little crack. I didn't see anything though and I stopped before damage was done.Since they are on a heater that's going to get thrown in the back of a trailer, my guess is that they will crack fairly soon. I'm just wondering if it will crack due to the heater being banged around, or if it will crack from heat or air movement.They also didn't come with screws. Not a huge deal, but just be prepared to have screws on hand.